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Bunt, or stinking
smut |
Causal organism - Ustilago nuda f.sp. tritici
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Control
The UK Seed Certification Scheme
is undoubtedly successful in ensuring that loose smut remains at very low
levels in UK seed stocks. Seed crops grown under the scheme are inspected
for loose smut and because the disease is so easily seen in crops very low
levels can be detected by visual examination of the growing crop.
Because the fungus invades the embryo
of the seed it is protected from the effects of surface acting seed treatments.
Until the 1960's a hot water steep (127-137º F) was the only method of
treating infected stocks. The
systemic fungicide carboxin was then introduced. Some strains of U.
nuda occurring on barley are now resistant to carboxin but other fungicides
are available.
Seed treatments specifically aimed at loose smut control are generally confined
to seed crops. It is seldom necessary to treat grain crops grown from bought
in seed as the UK Seed Certification Scheme precludes the sale of seed from
badly infected crops.
Varieties differ in their susceptibility to loose smut. There are, however,
several different races of the fungus and the longer a variety is grown the
more likely is its resistance to be eroded by the development of new races
to which it is susceptible.
